1. Technical Field
The present disclosure relates to a touch screen display, and more particularly, to a touch screen display without a separate touch panel.
2. Discussion of the Related Art
A touch screen display is used in personal digital assistants (PDAs), satellite navigation devices, and mobile communication devices such as a mobile phone. The touch screen display includes a liquid crystal panel which displays image information, a touch panel which is attached to the liquid crystal panel, a controller, a device driver and application software.
The liquid crystal panel includes a common electrode display panel having a common electrode and a thin-film transistor (TFT) display panel having a TFT array. The common electrode display panel and the TFT display panel face each other and are joined with each other by a seal line. The seal line is interposed between the common electrode display panel and the TFT display panel. A liquid crystal layer is formed in a gap between the common electrode display panel and the TFT display panel.
The liquid crystal panel displays an image when a voltage is applied to the electrodes disposed in the liquid crystal panel. The applied voltage rearranges liquid crystal molecules of the liquid crystal layer, thereby adjusting the amount of light that passes through the liquid crystal layer.
Since the liquid crystal panel is a non-light-emitting device, a backlight unit, which provides light, is disposed behind the TFT display panel. When light emitted from the backlight unit passes through the liquid crystal layer, the transmittance of the light is determined by the arrangement of liquid crystal molecules.
The touch panel includes two substrates which face each other, upper and lower conductive layers which are respectively formed on the two substrates, and a plurality of auxiliary spacers which are interposed between the upper and lower conductive layers. When a user presses a first point on the touch panel using a finger or a pen, the upper conductive layer and the lower conductive layer contact each other at the first point. The upper conductive layer and the lower conductive layer are electrically connected to each other at the first point. Accordingly, the location information of the first point is detected.
However, in a conventional touch screen display, a separate touch panel is attached to the touch screen display. The separate touch panel increases a thickness of the touch screen display. Without the separate touch panel, manufacture time and cost of the touch screen display can be reduced.